I am using TeXStudio and MikTex 2.9 (Windows 10).
My file was working properly until today and I did not change anything.
I've already tried renaming the file and change permissions (allow all changes) in the MikTex folder.
The error that appears is:
I can't write on file `tesis.pdf'. \includegraphics[width=4cm]{logo}
Here is my MWE

Are you sure that your tesis.pdf document is not already open before compilation in a pdf-reader which does allows for modification? That is what the error message suggests to me.
– DRiMar 24 '16 at 15:32

@DRi I have already checked that and it was not open
– LeilaMar 24 '16 at 15:34

Is the logo file in the same folder as titulo2.tex, not the one of the main file tesis.tex?
– DRiMar 24 '16 at 15:43

@DRi I have all the figures, including logo in the same folder, figuras. I have included in the preamble \graphicspath{{./figuras/}}
– LeilaMar 24 '16 at 15:54

Sorry,my previous command was wrong, you should have either: logo in the same folder as the main file and use \includegraphics[width=4cm]{logo} or logoin an other folder and use `\includegraphics[width=4cm]{figuras/logo}
– DRiMar 24 '16 at 15:59